TITLE:   GCN CIRCULAR
NUMBER:  32516
SUBJECT: GRB 220831A: DECam detection of a possible optical counterpart 
DATE:    22/09/02 15:47:51 GMT
FROM:    Anais Moller at Australian National U  <anais.moller@anu.edu.au>

GRB 220831A: DECam detection of a possible optical counterpart



J. Freeburn, N. Van Bemmel, D. Dobie, A. Moller, J. Cooke (Swinburne/OzGrav), M. Suhr (Swinburne/ASTRO 3D) report on behalf of the Deeper Wider Faster Collaboration



We have observed the Swift/BAT-GUANO localisation of GRB 220831A (GCN 32506) with the Dark Energy Camera (DECam) on the V. M. Blanco 4-m telescope. Imaging in g, r, i were carried out on UT dates 2022-08-31 and 2022-09-01 as part of an ongoing Deeper, Wider, Faster (DWF) program observing run.



We detect a source that is spatially coincident with the X-ray (GCN 32510) and near-infrared (GCN 32513) candidate counterpart and is not detected in archival imaging of the field.



RA = 01:37:0.965

DEC = -41:35:34.60



We measure:

59823.3  i = 23.13 +/-0.15

59824.3  i = 24.12 +/-0.28

59823.3  r = 23.06 +/-0.12

59824.3  r = 24.32 +/-0.20

59823.1  g < 23.9

59824.3  g < 24.6



Deep spectroscopy is encouraged. We will continue to monitor this source with DECam as part of DWF.